Application of bacterial agent YH for remediation of pyrene-heavy metal co-pollution system: Efficiency, mechanism, and microbial response

Xanthine oxidase driven bio-Fenton system for advanced pollutant degradation in sustainable wastewater treatment

Advanced oxidation processes such as the Fenton reaction are critical for degrading recalcitrant pollutants in wastewater but face operational bottlenecks. The classical Fenton process relies on hazardous exogenous H₂O₂, inefficient Fe2+/Fe3+ cycling, and stringent acidic pH, limiting scalability. To address these limitations, this study introduces a sustainable hybrid system integrating human xanthine oxidase (Hu-XO) with Fenton chemistry, enabling self-sufficient H₂O₂ generation, Fe redox cycling, and pH modulation. The Hu-XO-driven hypoxanthine/xanthine oxidation produced H₂O₂ and superoxide radicals, synergizing with Fe2+ to amplify hydroxyl radical generation. When optimized via response surface methodology (95 % model accuracy), the system achieved 91.8 % biochemical oxygen demand (BOD) and 86.0 % chemical oxygen demand (COD) reduction in tannery wastewater. The antimicrobial assay using Escherichia coli and Bacillus subtilis demonstrated a removal rate of up to 106 CFU/mL. Posttreatment toxicity assays revealed an 80 % decrease in Aliivibrio fischeri luminescence inhibition and restored seed germination rates for Vigna mungo, Vigna radiata, and Cicer arietinum. This work establishes a self-sustaining Fenton-based system that eliminates exogenous H₂O₂ dependence and strict pH requirements and integrates pollutant degradation with antimicrobial action, offering a scalable, eco-friendly strategy for industrial wastewater remediation.

Facile and green synthesis of Ag/Cu bimetallic nanoparticles using waste banana peel extract for effective corrosion inhibition of mixed sulfate-reducing bacteria

Microbiologically induced corrosion (MIC) is widespread in the oilfield industry, and new environmentally friendly materials are urgently needed to inhibit MIC with the increasing environmental requirements and microbial resistance problems. The synthesis method and cost of the materials are important factors that must be considered in the production and application. In this study, Ag/Cu bimetallic nanoparticles (BNPs) were synthesized by eco-friendly and sustainable method using waste banana peel extract (BPE) as a green reducing. The antibacterial and corrosion inhibition properties of Ag/Cu BNPs were investigated by using the enriched mixed strains containing sulfate-reducing bacteria (SRB) as model bacteria. The results of electron microscopy showed that the prepared BNPs exhibited spherical structure with about 19.0 nm in size. The synthesized nanoparticles significantly inhibited the growth of mixed strains by antimicrobial experiments with minimum inhibitory concentration (MIC) value of 9.38 μg/mL. The addition of Ag/Cu BNPs (9.38 μg/mL) inhibited the corrosion of X65 carbon steel induced by the mixed strains with 77.9% compared to the untreated condition. Correspondingly, the number of sessile SRB cells in the solution containing Ag/Cu BNPs (9.38 μg/mL) after 28 days of immersion decreased by 5-log compared with the treatment group without nanomaterials (1.1 × 108 cells/cm2). Furthermore, the observation of the surface morphology and strains cellular microstructure of carbon steel treated with nanoparticle materials illustrated that the corrosion inhibition mechanism mainly includes destroying cell structure, affecting metabolic activities and inhibiting biofilm formation. The environmentally friendly nanoparticle materials prepared in this study have great potential in the safe and clean production of oil fields.

New insights into the stages of cadmium remediation in ryegrass enhanced by kitchen compost-derived dissolved organic matter: Activation, absorption, and storage

Dissolved organic matter (DOM) regulates plant behavior in both agricultural and environmental fields. However, the regulatory mechanisms by which DOM influences soil-plant system interactions during the phytoremediation of Cd-contaminated soils remain unclear. Therefore, this study investigated the enhanced effect of kitchen compost-derived DOM on the Cd remediation capability of ryegrass across three phases of phytoremediation. The main pathways and mechanisms of DOM-assisted phytoremediation were identified through the analysis of changes in soil microbial communities and metabolism functions. The results revealed that DOM increased the bioavailability of soil Cd and significantly enhanced the Cd enrichment capacity of ryegrass, regardless of the application rate. The application of 20 % DOM to soil with a 20 mg/kg Cd content increased the bioconcentration factors of ryegrass roots and shoots by up to 38.19 and 11.08 times, respectively, compared with the control group. The direct or indirect optimizing effects of DOM on Cd fraction transformation, microbial communities, and their metabolism functions significantly enhanced the Cd enrichment capacity of ryegrass. Notably, DOM exhibited dual effects on ryegrass growth, mainly influenced by changes in soil physicochemical properties, optimization of microbial communities, and alterations in nitrogen metabolic functions. Additionally, the Cd reserves in ryegrass, which serve as a vital indicator of phytoremediation, exhibited a positive response to DOM. This study provides insights into the various reinforcing roles of kitchen compost-derived DOM in Cd-contaminated soil phytoremediation. These findings support the development of effective agronomic strategies for precise Cd regulation.

Fe3+/Fe2+ cycling drove novel ammonia oxidation and simultaneously removed lead, cadmium, and copper

The discharge of several pollutants, such as ammonia (NH4+-N), nitrate (NO3--N), and heavy metals, from aquaculture wastewater into the aquatic environment can cause severe pollution issues. In this work, microbial techniques were employed to enable concurrent elimination of NH4+-N and NO3--N by Fe3+/Fe2+ cycling. The greatest NH4+-N and NO3--N removal efficiencies of 96.1 % and 97.6 % were gained by Aquabacterium sp. XL4 at NH4+/NO3- ratio of 1:1, carbon to nitrogen ratio of 4.0, pH of 6.5, and Fe3+ dosage of 20.0 mg L-1. Inhibitor and nitrogen balance assays suggested that nitrogen removal process of strain XL4 was a coupled function of anaerobic ammonia oxidation, ferric reduction driven ammonia oxidation, and iron-based denitrification. Furthermore, under the compound influence of strain XL4 metabolic processes and microbial iron oxide adsorption, the removal efficiencies of Pb2+, Cd2+, and Cu2+ reached above 90 %. This work contributes to theoretical grounding for microbial removal of multiple pollutants.